The present disclosure relates to a photoelectric conversion element and a solid-state imaging apparatus.
Photoelectric conversion elements using an organic material (organic photodiodes) can photoelectrically convert only a specific color (wavelength zone). Due to this characteristic, when the photoelectric conversion elements are used as photoelectric conversion elements in a solid-state imaging apparatus, a structure in which sub-pixels are laminated can be obtained, which structure cannot be obtained from a known solid-state imaging apparatus constituted of sub-pixels, which are made of a combination of on-chip-color-filters (OCCF) and photoelectric conversion elements, in a two-dimensional array. The photoelectric conversion elements, accordingly, can receive incident light with high efficiency, and therefore a solid-state imaging apparatus using them can be expected to have higher sensitivity. In addition, the photoelectric conversion elements have an advantage in which false colors are not generated because of a lack of necessity of demosaic processing.
On the other hand, structures of organic photoelectric conversion elements used in solid-state imaging apparatuses are the same as or similar to those of various organic thin film photovoltaic cells (see, for example, Japanese Patent Application Laid-open No. 2006-339424, Japanese Patent Application Laid-open No. 2007-123707, Japanese Patent Application Laid-open No. 2007-311647, and Japanese Patent Application Laid-open No. 2007-088033), and improvement of photoelectric conversion efficiencies is aimed for.
In general, organic materials have higher resistance, and very lower mobility and carrier density than silicon semiconductor materials. Photoelectric conversion elements using the organic material, therefore, have not reached to show the characteristics of sensitivity and responsiveness comparable to those of photoelectric conversion elements using inorganic materials as typified by known silicon semiconductor materials.